Lurgi coal-gasification wastewater was degraded in supercritical water using Mn2O3, Co2O3, and CuO as catalysts. The experiments were performed in a batch reactor at temperatures of 380-460 degrees C and oxygen ratios of 1.5-3.5. The results involved evaluation of TOC and NH3-N removal efficiencies; detection of the main products in the effluent; XRD, SEM, and BET analyses of the catalysts; and detection of metal ions leached from the catalysts. Maximum TOC and NH3-N removals were found with Co2O3 catalyst at 460 degrees C and OR = 3.5. The effluent quality could meet class-I criteria of the Integrated Wastewater Discharge Standard (GB 8978-1996). The catalytic effects on pollutant removal were in the order Co2O3 > Mn2O3 > CuO. The major phase of Mn2O3 transformed into MnO2 with a decreasing BET surface area at 460 degrees C and an oxygen ratio of 3.5. Serious Cu-ion leaching occurred during the process and intensified with increasing temperature.